scholarly journals X-Ray Studies of Quasars and Active Galaxies with the Einstein Observatory

1980 ◽  
Vol 5 ◽  
pp. 677-687 ◽  
Author(s):  
William H.-M. Ku
Keyword(s):  
Statistical Tests ◽  
Cosmological Parameters ◽  
High Energy ◽  
Active Galaxies ◽  
X Ray ◽  
Upper Limits ◽  
Extensive Program ◽  
The Universe ◽  
Bl Lacs ◽  
Einstein Observatory

The launch of the Einstein Observatory has added a new and exciting dimension to the study of active galaxies. Not only have a large number of optical and radio active galaxies been detected, but many new examples of high energy activity have been found. The ease with which a large number of quasars may now be studied in the X-ray regime out to a redshift of at least four promises to improve our understanding of the nature of these tremendous powerhouses and the evolution of the universe.The Columbia Astrophysics Laboratory (CAL) is carrying out an extensive program to study active galaxies with the imaging proportional counter (IPC) on board the Einstein Observatory (Giacconi et al. 1979). These observations have already yielded a large number of positive detections including four Seyferts, five N galaxies, seven BL Lacs, and 17 quasars. Upper limits were obtained for eight additional quasars. Six new Seyfert I and/or quasars have been identified from X-ray observations (Chanan 1979). Preliminary results from the first six months of the CAL survey of active galaxies will be presented below. A few representative objects of interest will be discussed briefly. Simple statistical tests will be applied to determine whether X-ray properties can be used to understand the differences and similarities between the various classes of active galaxies. Particular emphasis will be placed on the quasars in our sample. Our results for the quasar survey will be compared with those discussed by Tananbaum et al. (1979). Finally, the implications of the discovery of a large number of quasars will be briefly discussed. (Cosmological parameters of qo = 0 and Ho = 50 km (s Mpc)-1 are used throughout.)

scholarly journals Hard X-Ray Properties of Cataclysmic Variables

1979 ◽  
Vol 53 ◽  
pp. 135-138
Author(s):  
J.H. Swank
Keyword(s):  
Solid State ◽  
Proportional Counter ◽  
Cataclysmic Variables ◽  
High Energy ◽  
X Rays ◽  
Dwarf Novae ◽  
X Ray ◽  
Upper Limits ◽  
Energy Detectors ◽  
Einstein Observatory

The production of hard X-rays in accretion onto degenerate dwarfs appears manifested by such sources as the magnetic variables AM Herculis and 3U0311-227 and the dwarf novae SS Cygni, EX Hydrae and U Geminorum. Upper limits on flux above 2 keV from Ariel 5 (Watson, Sherrington and Jameson 1978) and from the high energy detectors of the HEAO A2 experiment show that only a few others usually exhibit more than ~10-11 ergs cm-2s-1 or ~ 1031 ergs s-1. However, while there are only a few sources that these experiments could study, their behavior is complex (Swank et al. 1977a; Ricketts, King and Raine 1979; Swank et al. 1978; Mason, Cordova and Swank 1979). This paper is a brief summary of results for AM Her, EX Hya, SS Cyg and U Gem obtained with the high energy detectors of the HEAO A2 experiment from 2-60 keV and the Solid State Spectrometer Experiment (SSS) with the Monitor Proportional Counter (MPC) on the Einstein Observatory.

scholarly journals RS CVn Systems: The High Energy Picture

1983 ◽  
Vol 71 ◽  
pp. 415-427 ◽  
Author(s):  
P.A. Charles
Keyword(s):  
Line Emission ◽  
High Energy ◽  
Close Binaries ◽  
Stellar Rotation ◽  
Active Systems ◽  
X Ray ◽  
Coronal Activity ◽  
Solar Abundances ◽  
Scaled Models ◽  
Einstein Observatory

AbstractThe discovery of X-ray emission from RS CVn systems by HEAO-1 and subsequent surveys by the Einstein Observatory have shown that these close binaries exhibit greatly enhanced coronal activity. Here we review the 3 main observational areas: (1) results of the X-ray surveys of RS CVn systems and other late-type stars which indicate how the X-ray luminosity is correlated with the binary period (and hence stellar rotation) and other coronal activity indicators. This will be discussed in the context of scaled models of the solar corona; (2) X-ray spectroscopy of the most active systems which show multitemperature spectra and line emission consistent with solar abundances of the heavy elements; (3) observations of X-ray “flare-type” activity that has been associated with several RS CVn systems.

scholarly journals A NuSTAR view of powerful γ-ray loud blazars

2019 ◽  
Vol 627 ◽  
pp. A72 ◽  
Author(s):  
G. Ghisellini ◽  
M. Perri ◽  
L. Costamante ◽  
G. Tagliaferri ◽  
T. Sbarrato ◽  
...  
Keyword(s):  
Energy Distribution ◽  
Spectral Energy Distribution ◽  
Peak Frequency ◽  
High Energy ◽  
Spectral Energy ◽  
X Rays ◽  
X Ray ◽  
Γ Ray ◽  
The Universe ◽  
Jet Power

We observed three blazars at z >  2 with the NuSTAR satellite. These were detected in the γ-rays by Fermi/LAT and in the soft X-rays, but have not yet been observed above 10 keV. The flux and slope of their X-ray continuum, together with Fermi/LAT data allows us to estimate their total electromagnetic output and peak frequency. For some of them we were able to study the source in different states, and investigate the main cause of the different observed spectral energy distribution. We then collected all blazars at redshifts greater than 2 observed by NuSTAR, and confirm that these hard and luminous X-ray blazars are among the most powerful persistent sources in the Universe. We confirm the relation between the jet power and the disk luminosity, extending it at the high-energy end.

Sky survey of high-energy cosmic X-rays and spectral information on sources in the Crab nebula, Cygnus, and Scorpius

1968 ◽  
Vol 46 (10) ◽  
pp. S409-S413 ◽  
Author(s):  
Walter H. G. Lewin ◽  
George W. Clark ◽  
William B. Smith
Keyword(s):  
Crab Nebula ◽  
High Energy ◽  
X Rays ◽  
Coma Cluster ◽  
X Ray ◽  
Sky Survey ◽  
Upper Limits ◽  
Intensity Ratios ◽  
The Crab Nebula ◽  
Made In

A complete X-ray survey of the northern sky has been made in the energy range 20–100 keV. Spectra are given for Cyg X-1 and Tau X-1. Intensity ratios (Cyg X-1/Tau X-1) of 0.84 ± 0.10 and 1.30 ± 0.25 were derived in the 20–70 keV range from data obtained on July 19, 1966 and February 13, 1967, respectively. Observations on Sco X-1 and the Coma cluster show upper limits which are quite different from results reported by other groups.

scholarly journals COSMOLOGY WITH THE Ep,i – Eiso CORRELATION OF GAMMA–RAY BURSTS

2012 ◽  
Vol 12 ◽  
pp. 19-27 ◽  
Author(s):  
LORENZO AMATI
Keyword(s):  
Photon Energy ◽  
Energy Band ◽  
Gamma Ray ◽  
Cosmological Parameters ◽  
Gamma Ray Bursts ◽  
Spectral Peak ◽  
X Ray ◽  
Radiated Energy ◽  
The Universe

Gamma–Ray Bursts (GRBs) are the brightest sources in the universe, emit mostly in the hard X–ray energy band and have been detected at redshifts up to about 8.2. Thus, they are in principle very powerful probes for cosmology. I shortly review the researches aimed to use GRBs for the measurement of cosmological parameters, which are mainly based on the correlation between spectral peak photon energy and total radiated energy or luminosity. In particular, based on an enriched sample of 120 GRBs, I will provide an update of the analysis by Amati et al. (2008) aimed at extracting information on ΩM and, to a less extent, on ΩΛ, from the E p,i – E iso correlation.

scholarly journals GENERALIZED PARTICLE DYNAMICS IN ANTI-DE SITTER SPACES: A SOURCE FOR DARK ENERGY

2011 ◽  
Vol 20 (07) ◽  
pp. 1235-1249 ◽  
Author(s):  
SUDIPTA DAS ◽  
SUBIR GHOSH ◽  
JAN-WILLEM VAN HOLTEN ◽  
SUPRATIK PAL
Keyword(s):  
Dark Energy ◽  
Energy Equation ◽  
Cosmological Parameters ◽  
High Energy ◽  
Particle Dynamics ◽  
De Sitter ◽  
Acceleration Of The Universe ◽  
Sitter Background ◽  
Flrw Universe ◽  
The Universe

We consider the generalized particle dynamics, that we proposed [S. Das et al., J. High. Energy Phys.0904 (2009) 115] in braneworld formalisms for an asymptotically anti-de Sitter background. The present framework results in a new model that accounts for the late acceleration of the universe. An effective dark energy equation of state, exhibiting a phantom-like behavior, is generated. The model is derived by embedding the physical FLRW universe in a (4 + 1)-dimensional effective spacetime, induced by the generalized particle dynamics. We corroborate our results with present-day observed cosmological parameters.

scholarly journals The high energy Universe at ultra-high resolution: the power and promise of X-ray interferometry

2021 ◽  
Author(s):  
Phil Uttley ◽  
Roland den Hartog ◽  
Cosimo Bambi ◽  
Didier Barret ◽  
Stefano Bianchi ◽  
...  
Keyword(s):  
Strong Field ◽  
Imaging Spectroscopy ◽  
Hubble Constant ◽  
High Energy ◽  
Observable Universe ◽  
X Ray ◽  
Accretion Flows ◽  
High Energies ◽  
Light Echoes ◽  
The Universe

AbstractWe propose the development of X-ray interferometry (XRI), to reveal the Universe at high energies with ultra-high spatial resolution. With baselines which can be accommodated on a single spacecraft, XRI can reach 100 μ as resolution at 10 Å (1.2 keV) and 20 μ as at 2 Å (6 keV), enabling imaging and imaging-spectroscopy of (for example) X-ray coronae of nearby accreting supermassive black holes (SMBH) and the SMBH ‘shadow’; SMBH accretion flows and outflows; X-ray binary winds and orbits; stellar coronae within $\sim $ ∼ 100 pc and many exoplanets which transit across them. For sufficiently luminous sources XRI will resolve sub-pc scales across the entire observable Universe, revealing accreting binary SMBHs and enabling trigonometric measurements of the Hubble constant with X-ray light echoes from quasars or explosive transients. A multi-spacecraft ‘constellation’ interferometer would resolve well below 1 μ as, enabling SMBH event horizons to be resolved in many active galaxies and the detailed study of the effects of strong field gravity on the dynamics and emission from accreting gas close to the black hole.

scholarly journals The new “MUON G-2” result and supersymmetry

2021 ◽  
Vol 81 (12) ◽  
Author(s):  
Manimala Chakraborti ◽  
Sven Heinemeyer ◽  
Ipsita Saha
Keyword(s):  
Experimental Data ◽  
Dark Matter ◽  
Standard Model ◽  
Anomalous Magnetic Moment ◽  
Direct Detection ◽  
High Energy ◽  
Experimental Result ◽  
Susy Particle ◽  
Upper Limits ◽  
The Universe

AbstractThe electroweak (EW) sector of the Minimal Supersymmetric Standard Model (MSSM), with the lightest neutralino as Dark Matter (DM) candidate, can account for a variety of experimental data. This includes the DM content of the universe, DM direct detection limits, EW SUSY searches at the LHC and in particular the so far persistent $$3-4\,\sigma $$ 3 - 4 σ discrepancy between the experimental result for the anomalous magnetic moment of the muon, $$(g-2)_\mu $$ ( g - 2 ) μ , and its Standard Model (SM) prediction. The recently published “MUON G-2” result is within $${0.8}\,\sigma $$ 0.8 σ in agreement with the older BNL result on $$(g-2)_\mu $$ ( g - 2 ) μ . The combination of the two results was given as $$a_\mu ^{\mathrm{exp}} = (11 659 {206.1}\pm {4.1}) \times 10^{-10}$$ a μ exp = ( 11659 206.1 ± 4.1 ) × 10 - 10 , yielding a new deviation from the SM prediction of $$\Delta a_\mu = ({25.1}\pm {5.9}) \times 10^{-10}$$ Δ a μ = ( 25.1 ± 5.9 ) × 10 - 10 , corresponding to $${4.2}\,\sigma $$ 4.2 σ . Using this improved bound we update the results presented in Chakraborti et al. (Eur Phys J C 80(10):984, 2020) and set new upper limits on the allowed parameters space of the EW sector of the MSSM. We find that with the new $$(g-2)_\mu $$ ( g - 2 ) μ result the upper limits on the (next-to-) lightest SUSY particle are in the same ballpark as previously, yielding updated upper limits on these masses of $$\sim 750 \,\, \mathrm {GeV}$$ ∼ 750 GeV . In this way, a clear target is confirmed for future (HL-)LHC EW searches, as well as for future high-energy $$e^+e^-$$ e + e - colliders, such as the ILC or CLIC.

scholarly journals Abstracts

2011 ◽  
Vol 7 (S279) ◽  
pp. 433-446
Keyword(s):  
Gamma Ray ◽  
Cosmological Parameters ◽  
Supernova Explosion ◽  
Wide Band ◽  
High Energy ◽  
Gamma Ray Bursts ◽  
Core Collapse ◽  
Host Galaxies ◽  
Unique Type ◽  
X Ray

Measuring cosmological parameters with GRBs: status and perspectivesNew interpretation of the Amati relationThe SED Machine - a dedicated transient spectrographPTF10iue - evidence for an internal engine in a unique Type Ic SNDirect evidence for the collapsar model of long gamma-ray burstsOn pair instability supernovae and gamma-ray burstsPan-STARRS1 observations of ultraluminous SNeThe influence of rotation on the critical neutrino luminosity in core-collapse supernovaeGeneral relativistic magnetospheres of slowly rotating and oscillating neutron starsHost galaxies of short GRBsGRB 100418A: a bridge between GRB-associated hypernovae and SNeTwo super-luminous SNe at z ~ 1.5 from the SNLSProspects for very-high-energy gamma-ray bursts with the Cherenkov Telescope ArrayThe dynamics and radiation of relativistic flows from massive starsThe search for light echoes from the supernova explosion of 1181 ADThe proto-magnetar model for gamma-ray burstsStellar black holes at the dawn of the universeMAXI J0158-744: the discovery of a supersoft X-ray transientWide-band spectra of magnetar burst emissionDust formation and evolution in envelope-stripped core-collapse supernovaeThe host galaxies of dark gamma-ray burstsKeck observations of 150 GRB host galaxiesSearch for properties of GRBs at large redshiftThe early emission from SNeSpectral properties of SN shock breakoutMAXI observation of GRBs and short X-ray transientsA three-dimensional view of SN 1987A using light echo spectroscopyX-ray study of the southern extension of the SNR Puppis AAll-sky survey of short X-ray transients by MAXI GSCDevelopment of the CALET gamma-ray burst monitor (CGBM)

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